1. Field of the Invention
The present invention relates to an ultrasonic transducer associated with an electrode for real-time monitoring and feedback in a welding process.
2. Description of Related Art
The nondestructive testing of spot welds in real time using ultrasound has many advantages over other nondestructive approaches. Prior art arrangements include the insertion of the ultrasonic probe into the weld electrodes, with the acoustic energy sent through the weld subject. Then the analysis of the transmitted and/or reflected signal is performed in order to make some conclusions about the quality of the weld.
U.S. Pat. No. 3,726,130 discloses a probe glued to the back surface of the welding electrode. The probe generates a shear wave and receives a reflection from the primary solid-liquid interface of the weld. This method allows the determination of the penetration depth of the liquid zone into the subject. However, this method only gives information about one side of the weld, telling nothing about the opposite side. Also, as weld electrodes must be frequently changed or refreshed, this arrangement of the probe on the surface of the removable electrode can make it impractical or susceptible to damage in an industrial setting.
U.S. Pat. No. 4,099,045 discloses an acoustic wave undergoing multiple reflections within a weld subject. Evaluation of the degree of attenuation of the wave provides some information about the spot weld. This is an empirical approach which requires a collection of data for each particular case. The method enables prediction of the quality of the weld by comparison with previous results.
U.S. Pat. No. 6,297,467 discloses an electrode assembly incorporating ultrasonic probes and its basic principles of operation, and is hereby incorporated herein in its entirety.
It would be advantageous to provide a method of using acoustic waves to directly measure the dynamics of formation of weld and critical parameters which define the weld quality without comparing weld characteristics with previously tabulated results.